Air Conditioner Units with Improved Make-Up Air System

ABSTRACT

An air conditioner unit and methods of operating the same is provided. The air conditioner unit may include a refrigeration loop having a variable speed compressor, an electronic expansion valve, an indoor heat exchanger, and an outdoor heat exchanger. An indoor fan and an outdoor fan may be configured to urge air through the indoor and outdoor heat exchangers, respectively. A bulkhead may be disposed between the indoor heat exchanger and the outdoor heat exchanger to define an indoor portion and an outdoor portion of the unit. A vent aperture may be defined in the bulkhead, and the indoor and outdoor fans may be configured to urge make-up air from the outdoor portion through the vent aperture to the indoor portion. In addition, an auxiliary fan may be disposed within the vent aperture to provide additional “boost” make-up air, and a heating bank may be used to heat make-up air if desired.

FIELD OF THE INVENTION

The present disclosure relates generally to air conditioner units, and more particularly to air conditioner units that utilize an improved system for make-up air.

BACKGROUND OF THE INVENTION

Air conditioner or conditioning units are conventionally utilized to adjust the temperature indoors—i.e. within structures such as dwellings and office buildings. Such units commonly include a closed refrigeration loop to heat or cool the indoor air. Typically, the indoor air is recirculated while being heated or cooled.

A variety of sizes and configurations are available for such air conditioner units. For example, some units may have one portion installed within the indoors that is connected, by e.g., tubing carrying the refrigerant, to another portion located outdoors. These types of units are typically used for conditioning the air in larger spaces.

Another type of unit, sometimes referred to as PTAC or a packaged terminal air conditioner unit, may be used for somewhat smaller indoor spaces that are to be air conditioned. These units may include both an indoor portion and an outdoor portion separated by a bulkhead but e.g., supported within the same frame or casing. PTACs, for example, are sometimes installed in windows or positioned within an opening of an exterior wall of a building.

Frequently, the indoor space may need to draw in air from the outdoors—i.e. make-up air. For example, if a vent fan is turned on in a bathroom or air is otherwise ejected from the indoor space, fresh air from the outdoors is required. Depending on e.g., the efficiency of the weather stripping around doors and windows, this make-up air may simply be drawn into the indoors by cracks or other openings. If such cracks are not sufficient, the flow of make-up air may be insufficient or too slow. Furthermore, government regulations including e.g., fire codes may require that cracks or openings be eliminated as much as possible—precluding a sufficient flow of make-up air. Accordingly, an air conditioner such as e.g., a PTAC that can allow for the introduction of make-up air into the indoor space would be useful.

Sometimes air drawn from the outside as make-up air may be at the wrong temperature or humidity. For example, in the summer, the outdoor air may be too warm and too humid. In such case, it is undesirable to draw the air into the room with further conditioning—such as e.g., lowering its temperature and/or humidity. The opposite may be true in winter.

At the same time, however, the temperature and/or humidity of the air within the indoor space may already be at desired levels. As such, even if make-up air is needed, the operation of the air conditioner unit at full speed to condition the make-up air is inefficient. Furthermore, such operation can be generally noisier and more interruptive to the occupants of the indoor space.

Accordingly, improved air conditioner units and associated methods for providing make-up air are desired. In particular, air conditioner units and associated methods that can enable improved temperature and humidity control of make-up air would be useful. Such units that could also reduce noise and system complexity while improving efficiency would be particularly beneficial.

BRIEF DESCRIPTION OF THE INVENTION

The present subject matter provides an air conditioner unit and methods of operating the same. The air conditioner unit may include a system for providing make-up air into a room and conditioning that make-up air by controlling its temperature or humidity. The unit includes a refrigeration loop having a variable speed compressor that may operate at less than full speed for quieter and more efficient operation when full speed operation is not required. In addition, an auxiliary fan may provide additional “boost” make-up air, and a heating bank may be used to heat make-up air if desired. In this manner, the air conditioner unit may provide conditioned make-up air while operating at a more quiet and efficient operating point. Additional aspects and advantages of the invention will be set forth in part in the following description, may be obvious from the description, or may be learned through practice of the invention.

In accordance with one embodiment, an air conditioner unit for conditioning an indoor space is provided. The air conditioner unit includes an outdoor heat exchanger assembly disposed in an outdoor portion and including an outdoor heat exchanger and an outdoor fan; and an indoor heat exchanger assembly disposed in an indoor portion and including an indoor heat exchanger and an indoor fan. The unit further includes a compressor configured for circulating a refrigerant between the outdoor heat exchanger and the indoor heat exchanger and a bulkhead disposed between the outdoor heat exchanger and the indoor heat exchanger along a transverse direction, the bulkhead defining the indoor portion and the outdoor portion. A vent aperture is defined in the bulkhead and a damper is positioned proximate the vent aperture and configured to move between an open position where the outdoor portion is in fluid communication with the indoor portion and a closed position where the damper blocks the vent aperture to prevent fluid communication between the outdoor portion and the indoor portion. A controller is configured to open the damper and operate the indoor fan at less than full speed when a negative pressure condition is sensed to force make-up air out of the air conditioner unit.

In accordance with another embodiment, a method for providing make-up air from the outdoors through an air conditioner unit into an indoor space is provided. The air conditioner unit has an indoor portion with an indoor heat exchanger and an indoor fan, an outdoor portion with an outdoor heat exchanger, and a bulkhead positioned along a transverse direction between the indoor portion and the outdoor portion. The bulkhead defines an aperture between the indoor portion and outdoor portion. The method includes determining whether a negative pressure condition exists within the indoor portion of the air conditioner unit and, if a negative pressure condition exists, then opening the damper and operating the indoor fan at less than full speed to force make-up air through the air conditioner unit and into the indoor space.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.

FIG. 1 provides a perspective view of an air conditioner unit, with part of an indoor portion exploded from a remainder of the air conditioner unit for illustrative purposes, in accordance with one exemplary embodiment of the present disclosure.

FIG. 2 is a perspective view of components of an indoor portion of an air conditioner unit in accordance with one exemplary embodiment of the present disclosure.

FIG. 3 is a schematic view of a refrigeration loop in accordance with one embodiment of the present disclosure.

FIG. 4 is a rear perspective view of a bulkhead assembly in accordance with one embodiment of the present disclosure.

FIG. 5 is a top view of components of an air conditioner unit in accordance with one embodiment of the present disclosure.

FIG. 6 is a rear perspective view of components of an outdoor portion of an air conditioner unit in accordance with one embodiment of the present disclosure.

FIG. 7 is a rear perspective view of components of an outdoor portion of an air conditioner unit in accordance with one embodiment of the present disclosure.

FIG. 8 is a perspective section view of components of an air conditioner unit in accordance with one embodiment of the present disclosure.

FIG. 9 is a perspective section view of components of an air conditioner unit in accordance with one embodiment of the present disclosure.

FIG. 10 is a side section view of components of an air conditioner unit in accordance with one embodiment of the present disclosure.

FIG. 11 is a rear perspective view of an auxiliary fan positioned within a vent aperture in accordance with on embodiment of the present disclosure.

FIG. 12 illustrates a method for operating an air conditioner unit in accordance with one embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

Referring now to FIG. 1, an air conditioner unit 10 is provided. The air conditioner unit 10 is a one-unit type air conditioner, also conventionally referred to as a room air conditioner. The unit 10 includes an indoor portion 12 and an outdoor portion 14, and generally defines a vertical direction V, a lateral direction L, and a transverse direction T. Each direction V, L, T is perpendicular to each other, such that an orthogonal coordinate system is generally defined.

A housing 20 of the unit 10 may contain various other components of the unit 10. Housing 20 may include, for example, a rear grill 22 and a room front 24 which may be spaced apart along the transverse direction T by a wall sleeve 26. The rear grill 22 may be part of the outdoor portion 14, and the room front 24 may be part of the indoor portion 12. Components of the outdoor portion 14, such as an outdoor heat exchanger 30, outdoor fan 32, and compressor 34 may be housed within the wall sleeve 26. A casing 36 may additionally enclose the outdoor fan, as shown.

Referring now also to FIG. 2, indoor portion 12 may include, for example, an indoor heat exchanger 40, a blower fan 42, and a heating unit 44. These components may, for example, be housed behind the room front 24. Additionally, a bulkhead 46 may generally support and/or house various other components or portions thereof of the indoor portion 12, such as the blower fan 42 and the heating unit 44. Bulkhead 46 may generally separate and define the indoor portion 12 and outdoor portion 14.

Outdoor and indoor heat exchangers 30, 40 may be components of a refrigeration loop 48, which is shown schematically in FIG. 3. Refrigeration loop 48 may, for example, further include compressor 34 and an expansion device 50 (see also FIG. 6). As illustrated, compressor 34 and expansion device 50 may be in fluid communication with outdoor heat exchanger 30 and indoor heat exchanger 40 to flow refrigerant therethrough as is generally understood. More particularly, refrigeration loop 48 may include various lines for flowing refrigerant between the various components of refrigeration loop 48, thus providing the fluid communication there between. Refrigerant may thus flow through such lines from indoor heat exchanger 40 to compressor 34, from compressor 34 to outdoor heat exchanger 30, from outdoor heat exchanger 30 to expansion device 50, and from expansion device 50 to indoor heat exchanger 40. The refrigerant may generally undergo phase changes associated with a refrigeration cycle as it flows to and through these various components, as is generally understood. One suitable refrigerant for use in refrigeration loop 48 is 1,1,1,2-Tetrafluoroethane, also known as R-134A, although it should be understood that the present disclosure is not limited to such example and rather that any suitable refrigerant may be utilized.

As is understood in the art, refrigeration loop 48 may be alternately be operated as a refrigeration assembly (and thus perform a refrigeration cycle) or a heat pump (and thus perform a heat pump cycle). As shown in FIG. 3, when refrigeration loop 48 is operating in a cooling mode and thus performs a refrigeration cycle, the indoor heat exchanger 40 acts as an evaporator and the outdoor heat exchanger 30 acts as a condenser. Alternatively, when the assembly is operating in a heating mode and thus performs a heat pump cycle, the indoor heat exchanger 40 acts as a condenser and the outdoor heat exchanger 30 acts as an evaporator. The outdoor and indoor heat exchangers 30, 40 may each include coils through which a refrigerant may flow for heat exchange purposes, as is generally understood.

According to an example embodiment, compressor 34 may be a variable speed compressor. In this regard, compressor 34 may be operated at various speeds depending on the current air conditioning needs of the room and the demand from refrigeration loop 48. For example, according to an exemplary embodiment, compressor 34 may be configured to operate at any speed between a minimum speed, e.g., 1500 revolutions per minute (RPM), to a maximum rated speed, e.g., 3500 RPM. As explained in detail below, use of variable speed compressor 34 enables efficient operation of refrigeration loop 48 (and thus air conditioner unit 10), minimizes unnecessary noise when compressor 34 does not need to operate at full speed, and ensures a comfortable environment within the room.

In exemplary embodiments as illustrated, expansion device 50 may be disposed in the outdoor portion 14 between the indoor heat exchanger 40 and the outdoor heat exchanger 30. According to the exemplary embodiment, expansion device 50 may be an electronic expansion valve that enables controlled expansion of refrigerant, as is known in the art. More specifically, electronic expansion device 50 may be configured to precisely control the expansion of the refrigerant to maintain, for example, a desired temperature differential of the refrigerant across the indoor heat exchanger 40. In other words, electronic expansion device 50 throttles the flow of refrigerant based on the reaction of the temperature differential across indoor heat exchanger 40 or the amount of superheat temperature differential, thereby ensuring that the refrigerant is in the gaseous state entering compressor 34. According to alternative embodiments, expansion device 50 may be a capillary tube or another suitable expansion device configured for use in a thermodynamic cycle.

Bulkhead 46 may include various peripheral surfaces that define an interior 52 thereof. For example, and additionally referring to FIG. 4, bulkhead 46 may include a first sidewall 54 and a second sidewall 56 which are spaced apart from each other along the lateral direction L. A rear wall 58 may extend laterally between the first sidewall 54 and second sidewall 56. The rear wall 58 may, for example, include an upper portion 60 and a lower portion 64. Lower portion 64 may have a generally linear cross-sectional shape, and may be positioned below upper portion 60 along the vertical direction V. Rear wall 58 may further include an indoor facing surface and an opposing outdoor facing surface. The indoor facing surface may face the interior 52 and indoor portion 12, and the outdoor facing surface may face the outdoor portion 14. Bulkhead 46 may additionally extend between a top end 62 and a bottom end 66 along vertical axis V. Upper portion 60 may, for example, include top end 62, while lower portion 64 may, for example, include bottom end 66. Bulkhead 46 may additionally include, for example, an air diverter 68, which may extend between the sidewalls 54, 56 along the lateral direction L and which may flow air therethrough.

Upper portion 60 may have a generally curvilinear cross-sectional shape, and may accommodate a portion of the blower fan 42, which may be, for example, a centrifugal fan. Alternatively, however, any suitable fan type may be utilized. Blower fan 42 may include a blade assembly 70 and a motor 72. The blade assembly 70, which may include one or more blades disposed within a fan housing 74, may be disposed at least partially within the interior 52 of the bulkhead 46, such as within the upper portion 60. As shown, blade assembly 70 may for example extend along the lateral direction L between the first sidewall 54 and the second sidewall 56. The motor 72 may be connected to the blade assembly 70, such as through the housing 74 to the blades via a shaft. Operation of the motor 72 may rotate the blades, thus generally operating the blower fan 42. Further, in exemplary embodiments, motor 72 may be disposed exterior to the bulkhead 46. Accordingly, the shaft may for example extend through one of the sidewalls 54, 56 to connect the motor 72 and blade assembly 70.

Notably, according to an exemplary embodiment, outdoor fan 32 and blower fan 42 are variable speed fans. For example, referring to blower fan 42, motor 72 may be configured to rotate blade assembly 70 at different rotational speeds, thereby generating different air flow rates through blower fan 42. As explained herein, it may be desirable to operate fans 32, 42 at less than their maximum rated speed to ensure safe and proper operation of refrigeration loop 48 at less than its maximum rated speed, e.g., to reduce noise when full speed operation is not needed. In addition, as will be described below, fans 32, 42 may be operated to urge make-up air into the room.

According to the illustrated embodiment, blower fan 42 may operate as an evaporator fan in refrigeration loop 48 to encourage the flow of air through indoor heat exchanger 40. Accordingly, blower fan 42 may be positioned downstream of indoor heat exchanger 40 along the flow direction of indoor air and downstream of heating unit 44 along the flow direction of outdoor air (when make-up air is being supplied). Alternatively, blower fan 42 may be positioned upstream of indoor heat exchanger 40 along the flow direction of indoor air, and may operate to push air through indoor heat exchanger 40.

Heating unit 44 in exemplary embodiments includes one or more heater banks 80. Each heater bank 80 may be operated as desired to produce heat. In some embodiments as shown, three heater banks 80 may be utilized. Alternatively, however, any suitable number of heater banks 80 may be utilized. Each heater bank 80 may further include at least one heater coil or coil pass 82, such as in exemplary embodiments two heater coils or coil passes 82. Alternatively, other suitable heating elements may be utilized.

The operation of air conditioner unit 10 including compressor 34 (and thus refrigeration loop 48 generally) blower fan 42, outdoor fan 32 (FIG. 9), heating unit 44, expansion device 50, and other components of refrigeration loop 48 may be controlled by a processing device such as a controller 84. Controller 84 may be in communication (via for example a suitable wired or wireless connection) to such components of the air conditioner unit 10. By way of example, the controller 84 may include a memory and one or more processing devices such as microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of unit 10. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor.

Unit 10 may additionally include a control panel 86 and one or more user inputs 88, which may be included in control panel 86. The user inputs 88 may be in communication with the controller 84. A user of the unit 10 may interact with the user inputs 88 to operate the unit 10, and user commands may be transmitted between the user inputs 88 and controller 84 to facilitate operation of the unit 10 based on such user commands. A display 90 may additionally be provided in the control panel 86, and may be in communication with the controller 84. Display 90 may, for example be a touchscreen or other text-readable display screen, or alternatively may simply be a light that can be activated and deactivated as required to provide an indication of, for example, an event or setting for the unit 10.

Referring briefly to FIG. 4, a vent aperture 100 may be defined in the rear wall 58 of bulkhead 46. Vent aperture 100 may allow air flow therethrough between the indoor portion 12 and outdoor portion 14, and may be utilized in an installed air conditioner unit 10 to allow outdoor air to flow therethrough into the room through the indoor portion 12. In this regard, in some cases it may be desirable to allow outside air to flow into the room in order to compensate for negative pressure created within the room by, e.g., turning on a bathroom fan. In this manner, according to an exemplary embodiment, outside air, also referred to as make-up air, may be provided into the room through vent aperture 100 when a negative pressure is created as air is drawn out of the room by the bathroom fan.

As explained in detail below, blower fan 42 and outdoor fan 32 may be used to provide make-up air into the room when desired. However, referring now generally to FIGS. 4 through 11, air conditioner unit 10 may further include an auxiliary fan 102 (see FIGS. 10 and 11) that may be used with the existing refrigeration loop 48 force additional outdoor air through vent aperture 100. Auxiliary fan 102 may, according to the illustrated example embodiment, be positioned within outdoor portion 14 proximate to vent aperture 100. Additionally or alternatively, auxiliary fan 102 may be partially or wholly disposed in vent aperture 100 or partially or wholly disposed in indoor portion 12. Accordingly, auxiliary fan 102 may induce a flow of outdoor air from the outdoors through vent aperture 100 to the indoor portion 12.

As illustrated in FIG. 11, auxiliary fan 102 is a single fan disposed within vent aperture 100. Notably, if auxiliary fan 102 does not cover the entire vent aperture 100, gaps may allow air to flow around auxiliary fan 102 into indoor portion 12. In circumstances where it is desirable to force all outdoor air through auxiliary fan 102, covers may be placed over these gaps to prevent flow around auxiliary fan 102. According to another exemplary embodiment, more than one auxiliary fan may be used. In addition, according to an exemplary embodiment, a screen may be positioned over vent aperture 100 to capture and bugs or large particles in the flow of make-up air.

Auxiliary fan 102 may be used to determine whether there is a negative pressure in the room. In this regard, a negative pressure in the room will tend to draw air through vent aperture 100 if there are no other paths of least resistance. Therefore, negative pressure may cause air to flow through the blades of auxiliary fan 102 resulting in a force that rotates the auxiliary fan 102. As the auxiliary fan 102 rotates, it acts as a small generator, and the electricity it generates may be sensed as an indication of negative pressure. According to other exemplary embodiments, any other suitable air flow measurement device may be placed within unit 10 to determine when air is flowing through vent aperture 100 (and thus when there is negative pressure in the room).

A damper 104 may be pivotally mounted to the bulkhead 46 proximate to vent aperture 100 to open and close vent aperture 100. More specifically, according to the illustrated embodiment shown in FIG. 10, damper 104 is pivotally mounted to the indoor facing surface of indoor portion 12. Damper 104 may be configured to pivot between a first, closed position where damper 104 prevents air from flowing between outdoor portion 14 and indoor portion 12, and a second, open position where damper 104 is positioned parallel to a heat shield 106 (as shown in FIG. 10) and allows make-up air to flow into the room. According to the illustrated embodiment damper 104 may be pivoted between the open and closed position by an electric motor 108 controlled by controller 84, or by any other suitable method.

Notably, if damper 104 remains closed and completely prevents air from flowing from outdoor portion 14 to indoor portion 12 when a negative pressure condition exists, auxiliary fan 102 may not be used to detect negative pressure as described above. Therefore, according to some example embodiments, damper 104 may remain slightly open at all times such that when a negative pressure condition occurs, air may flow through vent aperture 100 to the extent minimally necessary to rotate auxiliary fan 102. Alternatively, damper 104 may be configured to create a light seal over vent aperture 100 such that a sufficient negative pressure within the room may cause damper 104 to open slightly. According to still another exemplary embodiment, damper 104 may remain completely closed and an alternative means for detecting negative pressure may be used, e.g., pressure sensors placed within outdoor portion 14 and indoor portion 12.

Referring now to FIGS. 9 and 10, air conditioner unit 10 may further include a temperature sensor 110 and a humidity sensor 112. Temperature sensor 110 and humidity sensor 112 may, for example, be disposed within indoor portion 12, and may be configured to measure the temperature and relative humidity, respectively, of air flowing into the room. As illustrated, sensors 110, 112 are positioned downstream of blower fan 42 and configured to measure the temperature and humidity of air right before it enters the room. However, one skilled in the art will appreciate that sensors 110, 112 may be positioned at any other suitable location within indoor portion 12, and that additional sensors may be used throughout unit 10. For example, sensors 110, 112 (or additional sensors) may be placed proximate to vent aperture 100 to sense the temperature and relative humidity of the make-up air flowing through vent aperture 100. Any suitable temperature sensor and humidity sensor may be utilized in accordance with the present disclosure.

Now that the construction of air conditioner unit 10 according to an exemplary embodiment has been presented, an exemplary method 200 of operating the make-up air feature of unit 10 will be described. Although the discussion below refers to the exemplary method 200 of operating air conditioner unit 10, one skilled in the art will appreciate that the exemplary method 200 is applicable to the operation of a variety of other air conditioning appliances having different configurations. For example, the present disclosure is further directed to other methods for operating air conditioner units 10 that facilitate improved operation, noise reduction, and increased efficiency. In exemplary embodiments, the various method steps as disclosed herein may be performed by controller 84.

Referring now to FIG. 12, method 200 includes, at step 210, determining whether the make-up air feature of air conditioner unit 10 is turned on. If the make-up air feature is off, damper 104 may be closed, such that air may not flow from outdoor portion 14 to indoor portion 12 through vent aperture 100. Alternatively, if the make-up air feature is on, regardless of other conditions sensed by air conditioner unit 10, step 220 includes determining whether a negative pressure exists within indoor portion 12 of unit 10. As explained above, a negative pressure condition may monitored using auxiliary fan 102 or by other means for determining a pressure differential between indoor portion 12 and outdoor portion 14. If there is not a negative pressure differential, damper 104 is closed and auxiliary fan 102 is turned off. In addition, outdoor fan 32 and blower fan 42 are turned off unless they are performing a normal air conditioning service.

If negative pressure is detected, make-up air must be supplied into the room. Therefore, when negative pressure is detected, damper 104 is opened at step 230 and make-up air is forced through vent aperture 100 into the room until pressure is equalized at step 240. As explained above, make-up air may be urged into the room using outdoor fan 32, blower fan 42, auxiliary fan 102, or some combination of the three, depending on the amount of make-up air needed. According to the exemplary embodiment, the make-up air feature is configured to operate in two different modes. More specifically, a user or operator of air conditioner unit 10 may select whether the make-up air feature operates in a low-speed or a high-speed mode.

For example, in the low-speed mode of operation, blower fan 42 may operate at approximately 25% of full speed to draw in make-up air through vent aperture 100. Alternatively, the speeds of the blower fan 42 and the outdoor fan 32 may be balanced to induce a flow, e.g., 25 cubic feet per minute (CFM), of make-up air into the room. In this manner, even if the air conditioner unit 10 is operating, for example, in the cooling mode, make-up air may still be provided by increasing the speed of blower fan 42 relative to outdoor fan 32, resulting in a net flow of make-up air through vent aperture 100.

In the high-speed mode of operation, auxiliary fan 102 may be operated simultaneously with fans 32, 42 to provide a larger amount of make-up air. For example, although controller 84 may be operable to activate and deactivate blower fan 42 when only low or moderate make-up air is desired, controller 84 may also operate both blower fan 42 and auxiliary fan 102 when a high-speed or “boost mode” is activated. This may be desirable, for example, when there is an increase in the negative pressure in the room, such as when a bathroom fan is set to a high-speed mode. It should be noted that outdoor fan 32 and blower fan 42 may be operable both simultaneously with and independently of auxiliary fan 102. In this manner, controller 84 may be provide versatile control over the amount of make-up air provided into the room by selectively operating outdoor fan 32, blower fan 42, and auxiliary fan 102.

In many cases, outdoor air may have a suitable temperature and humidity, and may therefore by provided directly through vent aperture 100 without activating refrigeration loop 48 to heat or dry the outdoor air. This may be true, for example, when the humidity in the outdoor portion 14 is below a predetermined humidity threshold and/or the temperature in the outdoor portion 14 is above or below a predetermined temperature threshold. In these cases, controller 84 may activate fans 32, 42, 102 independently of refrigeration loop 48 to encourage the flow of outdoor air through vent aperture 100, as discussed above.

However, in some cases, it may be desirable to treat or condition make-up air being flowed through vent aperture 100 prior to blowing it into the room. For example, outdoor air which has a relatively high humidity level may require treating before being flowed into the room. In addition, if the outdoor air is cool, it may be desirable to heat the air before blowing it into the room. Therefore, in addition to the make-up air operation, step 250 may include determining if air conditioning service is needed and step 260 may include operating refrigeration loop 48 and/or heating bank 44 to condition the make-up air if needed.

More specifically, according to an exemplary embodiment, if make-up air is being provided, but the relative humidity of the make-up air is higher than a predetermined threshold, refrigeration loop 48 may be used to remove moisture and lower the humidity of the make-up air. According to an example embodiment, controller 84 may be configured to operate refrigeration loop 48 when the humidity of the make-up air is above a predetermined threshold to lower its humidity. The predetermined humidity threshold may, for example, be between approximately 40% and approximately 70% relative humidity, such as between approximately 50% and approximately 60% relative humidity, such as approximately 55% relative humidity.

In addition, if the temperature in the room is above the set point temperature of the air conditioner unit, normal air conditioning service may be initiated by operated refrigeration loop 48 in the standard, full speed operation. Similarly, controller 84 may be configured to operate refrigeration loop 48 when the temperature of the make-up air is below a predetermined threshold to raise its temperature, e.g., to the set point temperature or another user controlled temperature. Alternatively, make-up air may also be heated using heating unit 44 of air conditioner unit 10 to raise the temperature of the make-up air to a predetermined temperature threshold. The predetermined temperature threshold may, for example, be between approximately 40° F. and approximately 60° F., such as approximately 50° F. Notably, various predetermined thresholds as discussed herein may, in some embodiments, be empirically determined and programmed into controller 84. Additionally or alternatively, various predetermined thresholds as discussed herein may be user adjustable, such as via user interaction with unit 10 via user inputs 88.

Make-up air may be provided and selectively conditioned by unit 10 until the air pressure between indoor portion 12 and outdoor portion 14 has equalized. After make-up air has equalized any pressure differential between outdoor portion 14 and indoor portion 12, and after that make-up air has been properly conditioned (if needed), damper 104 may be closed at step 270. Notably, even after damper 104 is closed and make-up air is no longer being provided, refrigeration loop 48 may still operate as usual to heat, cool, and/or dehumidify the room.

In this regard, as discussed above, air conditioner unit 10 may include controller 84, which is in communication with refrigeration loop 48 and other components of air conditioner unit 10. Controller 84 may additionally be in communication with temperature sensor 110 and humidity sensor 112. Thus, temperature sensor 110 and humidity sensor 112 may be utilized to control operation of the main refrigeration loop 48 and air conditioner unit 10. For example, according to some exemplary embodiments, controller 84 may be configured to activate refrigeration loop 48 at full speed, activate it at partial speed, or deactivate it based on temperature and/or humidity signals received from sensors 110, 112 by controller 84.

As explained above, controller 84 may operate refrigeration loop 48 in response to the humidity and temperature as measured by sensors 110, 112. However, one skilled in the art will appreciate that other sensors may be positioned throughout unit 10 and may be in communication with controller 84 to improve system performance. For example, unit 10 may further include additional indoor or outdoor temperature and humidity sensors, flow meters, and other suitable sensors.

Contrary to conventional air conditioner units which use a single speed compressor to circulate refrigerant within a refrigeration loop and an expansion valve (e.g., capillary tubes) designed to allow fixed expansion of refrigerant, air conditioner unit 10 uses a properly sized variable speed compressor 34. In this manner, low speed, quiet operation of air conditioner unit 10 may be achieved when full speed operation is not needed, e.g., when only dehumidification of the room is desired.

Thus, compressor 34 may be a variable speed compressor that may be operated at various speeds depending on the current air conditioning needs of the room. In order to prevent compressor 34 from overheating and to ensure proper operation of refrigeration loop 48, it is desirable that the rest of the components of thermodynamic system 48 also operate at a reduced rate. For example, electronic expansion valve 50 may be used to dynamically control the expansion of refrigerant and the temperature rise across indoor heat exchanger 40 as compressor speeds are adjusted. In addition, outdoor fan 32 and blower fan 42 may also be operated at speeds that correspond with the compressor speed. Notably, this means that refrigeration loop 48 may be operated at less than full speed without overheating compressor 34. This is beneficial for reducing noise and energy consumption when refrigeration loop 48 does not need to be operated at full speed.

For example, in a situation where make-up air is needed and dehumidification of that air is required, refrigeration loop 48 may operate at less than rated capacity, e.g., at 40% capacity. In addition, the speeds of the blower fan 42 and the outdoor fan 32 may be balanced to induce a flow, e.g., 25 cubic feet per minute (CFM), of make-up air into the room. In this manner, make-up air is provided and refrigeration loop 48 is operating at an optimal speed to condition and dehumidify that make-up air.

Alternatively, in a situation where make-up air is needed, but dehumidification is not required, refrigeration loop 48 may remain off, i.e., compressor 34 is not operating. In addition, outdoor fan 32 may be off and blower fan 42 may be set to operate at a speed that induces the flow of make-up air into the room, e.g., air flow at 25 cubic feet per minute (CFM). In this manner, make-up air is provided at the desired flow rate and has the desired temperature and humidity without the need for additional components or operation of refrigeration loop 48.

Such operation may advantageously increase the efficiency of the unit 10. For example, by operating refrigeration loop 48 at less than full speed, energy efficiency and system performance may be optimized, system noise may be reduced, and user comfort may be improved. Additionally, by operating the above-described air conditioner unit 10 in the above-described manner, unit 10 may provide dehumidified make-up air without additional thermodynamic assemblies by using the existing refrigeration loop to condition the make-up air. As a result, fewer components are needed, costs are reduced, assembly is simplified, reliability is increased, and maintenance costs are reduced.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

What is claimed is:
 1. An air conditioner unit for conditioning an indoor space, comprising: an outdoor heat exchanger assembly disposed in an outdoor portion and comprising an outdoor heat exchanger and an outdoor fan; an indoor heat exchanger assembly disposed in an indoor portion and comprising an indoor heat exchanger and an indoor fan; a compressor configured for circulating a refrigerant between the outdoor heat exchanger and the indoor heat exchanger; a bulkhead disposed between the outdoor heat exchanger and the indoor heat exchanger along a transverse direction, the bulkhead defining the indoor portion and the outdoor portion; a vent aperture defined in the bulkhead; a damper positioned proximate the vent aperture and configured to move between an open position where the outdoor portion is in fluid communication with the indoor portion and a closed position where the damper blocks the vent aperture to prevent fluid communication between the outdoor portion and the indoor portion; and a controller configured to open the damper and operate the indoor fan at less than full speed when a negative pressure condition is sensed to force make-up air out of the air conditioner unit.
 2. The air conditioner unit of claim 1, further comprising an auxiliary fan disposed at the vent aperture and configured to sense when there is a negative pressure condition in the indoor portion.
 3. The air conditioner unit of claim 2, wherein the controller is further configured to operate the auxiliary fan to force additional make-up air out from outdoors into the indoor space if the negative pressure condition is sensed and a boost mode is activated.
 4. The air conditioner unit of claim 3, wherein a make-up air flowrate when the boost mode is deactivated is about 25 cubic feet per minute and the make-up air flowrate when the boost mode is activated is about 50 cubic feet per minute.
 5. The air conditioner unit of claim 1, wherein the compressor is a variable speed compressor, the air conditioner unit further comprising: an electronic expansion valve configured to control the expansion of the refrigerant before it reaches the indoor heat exchanger; and a humidity sensor disposed within the indoor portion, wherein the controller is configured to operate the variable speed compressor, the outdoor fan, and the indoor fan at less than full speed and to operate the electronic expansion valve responsive to a speed of the variable speed compressor when an indoor humidity level sensed by the humidity sensor is above a predetermined humidity threshold.
 6. The air conditioner unit of claim 5, wherein the predetermined humidity threshold is greater than or equal to 55%.
 7. The air conditioner unit of claim 1, further comprising: a temperature sensor disposed within the indoor portion proximate the vent aperture to sense a temperature of make-up air; and a heater bank positioned within the indoor portion, wherein the controller is configured to activate the heater bank if the sensed temperature of the make-up air from the outdoors is below a predetermined temperature threshold.
 8. The air conditioner unit of claim 7, wherein the predetermined temperature threshold is a set point temperature of the air conditioner unit.
 9. The air conditioner unit of claim 1, wherein the damper is driven by an electric motor.
 10. The air conditioner unit of claim 1, wherein the controller is configured to close the damper when the negative pressure condition is not sensed.
 11. A method for providing make-up air from the outdoors through an air conditioner unit into an indoor space, the air conditioner unit having an indoor portion with an indoor heat exchanger and an indoor fan, an outdoor portion with an outdoor heat exchanger, a bulkhead positioned along a transverse direction between the indoor portion and the outdoor portion, the bulkhead defining an aperture between the indoor portion and outdoor portion the method comprising: determining whether a negative pressure condition exists within the indoor portion of the air conditioner unit and, if a negative pressure condition exists, then opening the damper and operating the indoor fan at less than full speed to force make-up air through the air conditioner unit and into the indoor space.
 12. The method of claim 11, wherein the air conditioner unit further comprises an auxiliary fan positioned adjacent to the vent aperture, and wherein the negative pressure condition is determined by sensing the rotation of the auxiliary fan.
 13. The method of claim 12, further comprising activating a boost mode so as to operate the auxiliary fan and force additional make-up air out through the air conditioner unit and into the indoor space if the negative pressure condition is sensed.
 14. The method of claim 13, wherein a make-up air flowrate when the boost mode is deactivated is about 25 cubic feet per minute and the make-up air flowrate when the boost mode is activated is about 50 cubic feet per minute.
 15. The method of claim 11, further comprising: providing a humidity sensor disposed within the indoor portion that is configured to measure the indoor humidity level and, if an indoor humidity level is above a predetermined indoor humidity level threshold, then operating a variable speed compressor, an outdoor fan, and the indoor fan at less than full speed, and operating an electronic expansion valve based on a temperature differential across the indoor heat exchanger.
 16. The method of claim 15, wherein the predetermined humidity threshold is greater than or equal to 55%.
 17. The method of claim 11, further comprising: sensing a temperature of the make-up air using a temperature sensor disposed within the indoor portion proximate the vent aperture; and activating a heater bank if the sensed temperature of the make-up air is below a predetermined temperature threshold.
 18. The method of claim 11, further comprising closing the damper when a negative pressure condition is not determined.
 19. An air conditioner unit for conditioning an indoor space, comprising: an outdoor heat exchanger assembly disposed in an outdoor portion and comprising an outdoor heat exchanger and a variable speed outdoor fan; an indoor heat exchanger assembly disposed in an indoor portion and comprising an indoor heat exchanger and a variable speed indoor fan; a variable speed compressor configured for circulating a refrigerant between the outdoor heat exchanger and the indoor heat exchanger; an electronic expansion valve configured to control the expansion of the refrigerant before it reaches the indoor heat exchanger; a bulkhead disposed between the outdoor heat exchanger and the indoor heat exchanger along a transverse direction, the bulkhead defining the indoor portion and the outdoor portion; a vent aperture defined in the bulkhead; a damper positioned proximate the vent aperture and configured to move between an open position where the outdoor portion is in fluid communication with the indoor portion and a closed position where the damper blocks the vent aperture to prevent fluid communication between the outdoor portion and the indoor portion; and a controller configured to open the damper and operate the variable speed compressor, the electronic expansion valve, the indoor fan, and the outdoor fan to induce and condition make-up air that passes through the vent aperture.
 20. The air conditioner unit of claim 19, further comprising an auxiliary fan disposed at the vent aperture and configured to force additional make-up air out from outdoors into the indoor space if a boost mode is activated. 